Question

the weight of a book at the surface of the Earth is 5 Newton what will be the weight of the same book at the height equal to the radius of the earth

Answer 1

first of all we find mass of the object which is equal an any where
m × g = 5
m = 5/g
at height R the value of acceleration due to gravity is G =g/(1+R/R)^2 =g / 4
were, R = radius of earth
hence,
at height R, weight = mass × G =(5/g) × (g/4)
=5/4 N